Control of fungi on cotton plants

ABSTRACT

MONOHYDRIC ALIPHATIC ALCOHOLS CONTAINING FROM 4 TO 12 CARBON ATOMS ARE EFFECTIVE IN THE CONTROL OF MICROORGANISMS WHICH CAUSES DISEASES OF PLANTS SUCH AS COTTON OR WHICH PRODUCE TOXINS THAT IMPAIR THE USEFULNESS OF PRODUCTS OF PLANTS INTENDED FOR HUMAN OR ANIMAL COMSUMPTION SUCH AS COTTONSEED OIL OR MEAL.

United States Patent O 3,778,509 CONTROL OF FUNGI ON COTTON PLANTS Harold Loyd Lewis, Raleigh, N.C., assignor to Cotton, Incorporated, New York, N.Y. N Drawing. Filed May 28, 1971, Ser. No. 148,178 Int. Cl. A01n 9/24 US. Cl. 424-343 ABSTRACT OF THE DISCLOSURE Monohydric aliphatic alcohols containing from 4 to 12 carbon atoms are effective in the control of microorganisms which cause diseases of plants such as cotton or which produce toxins that impair the usefulness of products of plants intended for human or animal consumption such as cottonseed oil or meal.

BACKGROUND OF THE INVENTION Microorganisms, including a wide variety of fungi, are responsible for attacking plants such as cotton in a number of ways. For instance, a particularly widespread form of cotton disease is that caused by microbial attack of cotton bolls, resulting in what is commonly known as boll rot. Boll rot is preceded by sparse growth of vegetative mycelia on the surface of bolls when they are younger than about 35 days. Bolls older than about 35 days become susceptible to attack by the microbes present on their surfaces. The degree of infection depends on temperature and humidity conditions. Once bolls are extensively penetrated, they are rendered essentially useless for textile purposes. Losses due to boll rot often run as high as 15% per annum.

The microorganisms primarily responsible for attacking cotton bolls are reported to be Fusarium oxysporum', Fusarium roseum', Fusarium moniliforme, F usarium solani, Verticillium nigrescens, Rhizoctom'a solanz', Diplodia gossypina, Phytophthora parasitica, Phomopsis gossypii, Collectotrichum gossypz'i and Xanthomonas malvaearum. Other microorganisms associated with the boll rot complex include Thielaviopsis basaco la, Glomerella gossypii and Pythium irregulare.

In addition, cottonseed meal, which is used as feed for livestock, is a host for a number of species of ailatoxinproducing microorganisms. Aflatoxins have been reported to be responsible for toxicosis in cattle, sheep and swine. See Goldblatt, Afiatoxin: Scientific Background, Control and Implications, Academic Press, New York, 1969, page 422. Known afiatoxin-producing fungi include various strains of Aspergillus flavus, Aspergillus oryzae and Aspergillus paraciticus.

Although ethylene dibromide has been elfectively used as a soil fumigant in the control of Fusarium, no commercially attractive non-phytotoxic or ecologically acceptable chemical composition has been found which may be applied directly to a crop such as cotton which is effective against all microorganisms causing boll rot and against those producing aflatoxins. For these reasons, cotton growers have continued to search for such chemical control agents.

It is a primary object of the present invention to provide for improved control of microorganisms responsible. for diseases in cotton or other field crops. It is a more specific object of this invention to increase the yield of cotton by treating it prior to harvest with a chemical agent which is sutiiciently stable to control boll rot over a period ranging from seven days to two months or more depending on environmental conditions. In the event of extended periods of high temperatures and humidity, multiple applications may be needed. The agent thus gives adequate 11 Claims 3,778,509 Patented Dec. 11, 1973 operational flexibility, but has a low persistence in the soil and is biodegradable.

It is another object of this invention to provide an effective fungicide against aflatoxin-producing fungi.

SUMMARY OF THE INVENTION It has now been discovered that boll rot and other discases of plants or associated with plants which are caused by microorganisms may be controlled by treating the plants or the susceptible parts thereof, such as cotton bolls, with compositions containing a monohydric alcohol having from 4 to 12 carbon atoms, preferably 6 to 10 carbon atoms in the case of cotton, or mixtures thereof, as an active biocide. In broad compass, the hydrocarbon structure of the alcohol may be linear or branched-chain aliphatic, saturated or unsaturated, or cycloaliphatic. The hydroxyl groups of the alcohol may be attached to a primary, secondary or tertiary carbon atom, but primary alcohols are preferred because they are fungitoxic at lower concentrations. The phytotoxicity of the alcohols toward the cotton plant tends to increase with decreasing alcohol chain length, while fungitoxicity tends to decrease with decreasing chain length, C being optimum for both high fungitoxicity and low phytotoxicity in the case of cotton.

Besides cotton, plants which can benefit from such treatment include grasses such as corn and other grains, and citrus and other fruit trees. The invention is also useful in the drying and storage of fruit, e.g. in the production of prunes or dried apricots.

The preferred usage form in this invention is an aqueous solution or suspension containing the active compound as the essential active microbial control agent.

Exemplary primary linear alcohols which have been found to be elfective as microbial control agents for cotton are l-hexanol, l-heptanol, l-octanol, l-nonanol and l-decanol. Branched primary alcohols such as 2-ethylhexanol and the more highly branched alkanols resulting from the oxo process, such as isooctyl and isodecyl alcohols, may also be used but are less desirable because they are less readily biodegradable. l-decanol is particularly preferred as the active microbiocidal agent, since it exhibts a very high toxicity in very low concentrations to a wide variety of deleterious microorganisms while having low phytotoxicity.

Examples of linear secondary alcohols effective in the present invention include 2-hexanol, 3-hexanol, 2-heptanol, 3-heptanol, 2-octanol, 4-octano1, 2-nonanol, 3-honanol, 2-decanol, 4-decanol and S-decanol.

Effective branched chain and tertiary alcohols include 3-methyl-3-pentanol, 3-ethyl-3-hexano1, 3-methy1-3-heptanol, and 3,6-dimethyl-3-octanol.

Ethylenically and acetylenically unsaturated alcohols are also effective fungicides but are not readily biodegradable and are toxic to humans and other mammals. Phenols and cyclic alcohols are not desirable for the same reasons.

Boll rot may be controlled in accordance with this invention by treating the bolls of the cotton plant with one or more of the active alcohols, or with a composition containing one or more of such compounds as its essential active ingredient, at a time when the bolls are from 35 to 45 days old.

Since cotton plants in a given plot may flower over a period as long as 30 to 60 days, it is advantageous to make the first application about 35 to 45 days after first flower depending on location, variety, planting patterns and weather conditions. In this manner, two or three applications will usually suffice to control boll rot in all of the plants in a given field. The second application may be made about 7 to 14 days after the first, and the third application may follow the second by about 7 to 14 days.

The need for as well as the timing of such subsequent applications will depend upon the developmental stage of the bolls and weather conditions.

Each application should cover the entire field or orchard, and the rate of application should be from about 1 to pounds of the active compound per acre of cotton, though higher rates of up to about 12 pounds or more per acre as well as rates as low as about 0.2 pound per acre can be used. The optimum amount will vary somewhat depending on the specific treating composition applied, environmental conditions, time of year, age and size of the cotton or other plants being treated, but can be readily determined for a given case by preliminary testing.

A number of the active cotton disease control compounds of the present invention have also been found to be very effective in the control of the microorganism Helminthotrporum maydis, which is primarily responsible for the southern leaf blight disease in corn plants. Effective compounds include the linear primary alcohols containing from 6 to 10 carbon atoms. l-decanol has been found to be especially effective in the control of southern leaf blight when used in treating corn plants according to the same technique herein disclosed as useful in the treatment of cotton.

The active agent is conveniently applied in the field in the form of an aqueous solution or suspension, e.g., a liquid composition which may be sprayed from a boomspray or a solid dust composition where the active compound is diluted with an inert solid such as clay and which can be applied as a dust from an airplane.

With the type of boom-spray apparatus used in this work, it is convenient to appl the active compound to the cotton field in the form of an aqueous solution, suspension or emulsion having a concentration of active agent such that the application at the rate of from 50 to 100 gallons of liquid composition per acre will provide the required dosage of active chemical. However, the use of lower or high gallonages may be preferred when a different dispensing mechanism is used.

Water is the preferred liquid carrier for the active biocidal agents in practicing the present invention. Most of the compounds of interest are liquids under normal arnbient conditions, though the solid species falling within the scope of the present invention are similarly useful. When water is used as the carrier, from about 0.001 to about 10 percent by weight of a cationic, anionic or nonionic surfactant is generally necessary, both to promote spreading and to reduce phytotoxicity. Preferably the ratio of active alcohol to surfactant is from 10:1 to 1:10. Suitable surfactants include polyoxyethylene sorbitan esters, polyoxyethylene alcohols, alkylarylpolyether alcohols, phthalic glycerol alkyl resins, ethoxylated imidazoline, decanoic acid, diglycol oleate, polyether sulfonates, alkylaryl sulfonates, and mixtures thereof.

A particularly preferred group of surfactants are the polyoxyethylene sorbitan monoesters, such as the laurates, palmitates and oleates. The preferred average number of oxyethylene groups per molecule is about 20, although sorbitan monoesters containing from about 10 to about 30 oxyethylene groups per molecule are similarly useful.

Instead of using water as the carrier, non-phytotoxic mineral oils either as such or in the form of Water-in-oil or oil-in-water emulsions may be used similarly in accordance with practices which are common to the art of treating vegetation with beneficial growth control agents.

Other active ingredients, such as known growth control agents and known insecticides, are not required but may be included in the compositions of the present invention in order to obtain a desired result, such as the simultaneous control of boll worms in cotton plants.

Suitable insecticides used for cotton insect control include those registered for use on cotton by the Department of Agriculture. Exemplary compounds include 2-methyl-2-(methylthio)propionaldehyde O-(methylcarbamoyl)oxime,

0,0-diethyl phosphorodithioate S-ester with 3-(mercaptomethyl) 1 ,2,3-benzotriazin-4 3H -one,

0,0-dimethyl phosphorodithioate S-ester with 3-(mercaptomethyl 1 ,2,3-benzotriazin-4 3H) -one,

l-naphthyl methylcarbamate,

S-[ (P-Chlorophenyl) thio] methyl] 0,0-diethyl phosphorodithioate,

at least 60 percent of l,2,4,5,6,7,8,8-octachloro-2,3,3a,4,

7,7a-hexahydro-4,7-methanoin-dene and not over 40 percent of related compounds,

ethyl 4,4-dichlorobenzilate,

mixture of 0,0-diethyl S(and O)-[Z-(ethylthio) ethyl] phosphorothioate,

0,0-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate,

4,4-dichloro-alpha-(trichloro methyl)benzhydrol,

3-hydroxy-N,N-dirnethyl-cis-crotonamide dimethyl phosphate,

not less than percent of 1,2,3,4,10,10-hexachloro-6,7-

epoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4-endo-exo-5,8- dimethanonaphthalene,

O,-O-dimethyl S-(N-methylcarbamoylmethyl) phosphorodithioate,

0,0-diethyl S-[Z- (ethylthio)ethyl] phosphorodithioate,

6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-

methano-2,4,3-benzodioxathiepin 3-oxide,

1,2,3,4,10,l0-hexachloro-6,7-epoxy1,4,4a5,6,7,8,8a-

octahydro-1,4-endo-endo-5,8-dimethanonaphthalene,

O-ethyl-O-p-nitrophenyl phenylphosphonothioate,

0,0,0',O'-tetraethyl S,S'-methylenebisphosphorodithioate,

S-[ l,2-bis(ethoxycarbonyl) ethyl] 0,0-dimethy1 phosphorodithioate,

0,0-dimethyl O-p-nitrophenyl phosphorothioate,

S-[[(p-chlorophenyDthio]methyl] 0,0-dimethyl phosphorodithioate,

3-hhydroxy-N-methyl-cis-crotonamide dimethyl phosphate,

1,2-dibromo-2,2-dichloroethyl dimethyl phosphate,

0,0-diethyl O-p-nitrophenyl phosphorothioate,

0,0-diethyl S-[(ethylthio)methyl] phosphorodithioate,

2-chloro2-diethylcarbamoyl-l-methylvinyl dimethyl phosphate,

terpene polychlorinates containing 65 percent chlorine, sulfur, chlorinated camphene containing 67 to 69 percent chlorine, and dimethyl (2,2,2-trichloro-1-hydroxyethyl)phosphonate.

Such insecticides are preferably included in a composition containing the active fungicidal compound in an amount such that between about 0.25 and 5 pounds per acre are applied. For example, the insecticide comprising terpene polychlorinates containing 65 percent chlorine (commonly known as Toxaphene) should 'be used in an amount from about 1 to about 4 pounds per acre. Dimethyl (2,2,2 trichloro 1 hydroxyethyl)phosphonate (commonly known as "lrichlorfon) may be included in the fungicidal composition in an amount so that from about 1 to about 3 pounds per acre are applied.

The insecticides 0,0-dimethyl phosphorodithioate S- ester with 3-(mercaptomethyl)-1,2,3-benzotriazin-4(3H)- one (sold by Bayer as Guthion), l-napthyl methylcarbamate (sold by Union Carbide as Sevin), 3-hydroxy-N- methyl-cis-crotonamide dimethyl phosphate (sold under the tradename Azodrin by Shell Oil Co.), and 0,0- dirnethyl 0 p nitrophenyl phosphorothioate (commonly known as Methyl Parathion) are especially useful for the control of the pink =boll worm in cotton plants, which aggravates the boll rot problem. Guthion should be applied in an amount from about 0.15 to about 2, preferably from about 0.25 to 1 pound per acre, while Sevin" may be applied in an amount from about 0.25 to 4, preferably from about 0.5 'to 3 pounds per acre. Azodrin is most effective in an amount from about 0.15 to 2, preferably 0.3 to 1 pound per acre. The insecticide Methyl Parathion is effective against the pink boll worm and other insects when applied in an amount from about 0.15 to 4, preferably from about 0.25 to 3 pounds per acre.

Phytotoxicity of some of the active alcohols is in 6 Examples 1618 The following examples illustrate the inhibitory eifect that the active alcohols exert upon aflatoxin-producing microorganisms. Gradient plates prepared as in Examples 1-9 were injected with various strains of Aspergillus spp.,

general low. For example, concentrations as high as 5 which are known aflatoxin producing fungi (numbers 3% 3 i f i i. gif gg fi refer to the Northern Regional Research Laboratory culno a verse 6 cc upon See E gefmma g ture collection). The pates were also injected as in coinPounds f i present Invention have been known Examples 1-9 with various alcohols at the concentrations to exh bit a selectivity for the removal of the merlstems 10 and PH indicated in Table m. The percentage growth of of various plants, and may therefore be useful as chemical all of the strains tested was essentially zero. prunmng agents when desired, this eifect may be d1- rninished or blocked altogether by choosing a suitable TABLE 111 alcohol species or by maintaining a low alcohol to sur- Concenfactant ratio mtim 1 Alcohol (percent) pH Aspergillus strain DESCRIPTION OF SPECIFIC EMBODIMENTS Example b Examples 1-9 at 1h 1 3. 2.114101031156157. Gradient plates containing a Saborauds nutrient agar exam) 110 31 215 1 50 11 1327'. (a glucose peptone medium) were prepared according to 17 1 t 1 0 g 5 the 'Szybalski method and inoculated with 1 to 2 ml. of a '00 am ofos s10 aifiiir'fi m'z spore inoculum containing 1 10 spores/ml. of the 18"; Ldecanol 3:82 8 ifif 'ff fif microorganisms indicated in Table I. The proper amount 0. 03 8.0 A. flaws 3517. of a filter sterilized alcohol was blended into a known volume of molten agar medium under sterile conditions The results show that the alcohols are effective against to yield the desired concentration ranging from 0.03 to a broad range of known aflatoxin-producing microorgan- 1% as indicated, and allowed to incubate for a period isms and are relatively independent of the normal pH up to 14 days at 25 to 28 C., intermittent readings being fo d on t l taken to observe if any growth had taken place. The E 1 19 growth in all cases was essentially zero at the concentra- 30 Xamp e tionsindicatedinTable I. A mixture of n-octanol and 55% n-decanol as TABLE I Concentration Alcohol (percent) Microorganism Example Number:

1.0 Fusariumozysporum. 1 mm :83 itillttolttttfttf 03 Xa'nthomonas malvaccaru'm. 1 2 1-hexyn3ol...:.:.:.;.:;..-- 0.1 Fusuriumozysporum. R Q-haptnnnl 1.0 Fusariumsolani. .03 Fusariumsolant. 4 lmnmm'] .03 Rhizocto'rtjasolam.

. 03 Collectotnchum 903311111126. .03 Puthiumirreaulea. 5"; 1-ethynyl-1-eyclohexanol-..- .25 Fusariumozysporum. n Z-fl 1.0 Fuscriumaolina.

.03 Fusariumozysporum. 03 Verticillimn m'grescem. 7 l-demmnl I .03 Glomerellaaosaypi'na.

03 Helmnthosporum muydis. 03 Thielcviopsis basacolc. 8...'..'.-...-.- 3,6-dimethyl-3-oetanol......-. .01 Fusan'u'm oxysporum. 9 4-ethy1-1zhexyn-3-ol 0.1 Fusuriumoxusporum.

1x10 sporeslml.inoculum.

Examples 10-15 active ingredients was applied to 2 acres of American Gradient plates of the type Set forth in Examples upland cotton plants when about of the bolls were were prepared and inoculated in the same manner as in 35 days old by means. of a commercial spraymg'. The Examples 1-9 with aqueous solutions of alcohols addialcohols were Rresent a concentrauon of 1% m an tionally containing a surfactant of polyoxyethylene sorbi- P Suspenswn coiltalmng of a polyethoxylzlted tan monooleate (sold by Atlas Powder Company under sPrbltan monooleate (Tween 80 The e f the tradename Tween 80) for all but Examples 14 and was 74 gallons 1 acre and one a'pplmatlm was 15, which were polyoxyethylene sorbitan monolaurate made- (Tween 20) in the concentration indicated in Table II. The percentage growth of the microorganisms indicated was essentially zero.

The treated plot exhibited an increase in yield of about 10% as compared to an untreated control plot of the same acreage.

The invention described above is particularly pointed out in the following claims, it being understood that it may be varied or modified in Ways that may occur to those skilled in the art, without departing from the scope or spirit hereof.

I claim:

1. A method for the control of Fusariwm otxysporum on cotton plants which comprises treating said cottom plants with a fungicidally effective amount of a monohydric aliphatic alcohol containing from 6 to 10 carbon atoms per molecule.

2. A method for the control of Xanthomonas malvaciarum on cotton plants which comprises treating said cotton plants with a fungicidally elfective amount of a monohydric aliphatic alcohol containing from 6 to 10 carbon atoms per molecule.

3. A method for the control of Collectotrichum gossypii on cotton plants which comprises treating said cotton plants with a fungicidally effective amount of a monohydric aliphatic alcohol containing from 6 to 10 carbon atoms per molecule.

4. A method for the control of Thielaviopsis basacola on cotton plants which comprises treating said cotton plants with a fungicidally effective amount of a monohydric aliphatic alcohol containing from 6 to 10 carbon atoms per molecule.

5. A method for the control of Fusarz'um solani on cotton plants which comprises treating said cotton plants with a fungicidally effective amount of a monohydric aliphatic alcohol containing from 6 to 10 carbon atoms per molecule.

6. A method for the control of Diplodia gossipina on cotton plants which comprises treating said cotton plants with a fungicidally effective amount of a monohydric aliphatic alcohol containing from 6 to 10 carbon atoms per molecule.

7. A method for the control of Rhizoctonia solam' on cotton plants which comprises treating said cotton plants with a fungicidally elfective amount of a monohydric aliphatic alcohol containing from 6 to 10 carbon atoms per molecule.

8. A method for the control of Aspergillus flavus on cotton plants which comprises treating said cotton plants with a fungicidally efiective amount of a monohydric aliphatic alcohol containing from 6 to 10 carbon atoms per molecule.

9. A method according to claim. 1 wherein said alcohol is applied at a rate of from about 1 to about 10 pounds of the alcohol per acre.

10. A method according to claim 9 wherein said alcohol is applied to the cotton plants as an aqueous suspension of from about 0.01 to about 1% by weight of the alcohol and from about 99 to about 99.99% by weight water.

11. A method according to claim 10 wherein said suspension further contains from about 0.001% to 10% by weight of a surfactant.

References Cited UNITED STATES PATENTS Re. 20,869 10/ 1938 Bousquet et al. 424343 Re. 20,869 10/1938 Bousquet et al. 424-343 1,920,026 7/ 1933 Tischler 424343 2,254,665 9/1941 Ralston et al 424343 FOREIGN PATENTS 1,693,734 3/1934 Australia 424343 237,408 8/1911 Germany 424343 565,473 11/ 1944 Great Britain 424-343 1,693,734 3/ 1934 Australia 424-343 ALBERT T. MEYERS, Primary Examiner D. W. ROBINSON, Assistant Examiner 

